The present invention relates to orthopedic medical apparatus and more particularly to medical apparatus utilized to treat bone fractures wherein repositioning and immobilization of the fractured bone is facilitated by means external of the body soft tissue; such apparati are referred to very broadly as external fixation devices.
External fixation has long been recognized as a viable means for treating fractures of the bones, with the first reasonably successful use of such external fixation devices being traced back to the early 20th century. Since its inception, there have been various external fixation systems developed, all of which in one form or another utilize a plurality of transfixing and/or half pins which extend through the bone and outward beyond the soft tissue surrounding the bone. The multiple pins are positioned on opposite sides of the fracture and rigidly attached to one or more pin couplings at their distal ends. The pin couplings are interconnected by a mounting bar which permits the bone portions located on opposite sides of the fracture to be repositioned relative one another and maintained in an aligned position which after a sufficient period of time, permits proper healing of the fracture. Although such prior art external fixation apparatus has proven useful in specific applications, there are inherent deficiencies associated in its general use.
Foremost of these deficiencies is the prior art's inability to provide sufficient rigidity to ensure complete immobilization of the bone fracture during the rehabilitation period. This lack of rigidity focuses upon the prior art's typical use of the transfixing pins themselves to form the major portion of the exterior load bearing structure of the device. Although the transfixing pins are typically fabricated from hardened stainless steel, due to their substantial length in relation to their cross-sectional area, they tend to moderately flex when subjected to tensile and bending forces. Such flexing permits the bone portions to move relative one another during movement of the patient's limb extremities, thereby varying the bone placement and detracting from the healing process.
Additionally, the prior art external fixation device has typically comprised rather large bulky mechanical apparatus which extends substantially outward beyond the soft tissue in the vicinity of the fracture. Such outward protrusion and bulkiness of the fixation structure not only results in uncomfort to the patient but in the case of an open fracture, limits access to the soft tissue making necessary treatment of the soft tissue such as skin grafting or irrigation difficult.
Further, the prior art external fixation devices have heretofore facilitated only limited pin placement and have failed to provide any means for the independent removal or adjustment of individual pins on the apparatus without disturbing the remaining pins of the external fixation. As such, the prior art devices have often limited the orthopedic surgeon during operative installation of the device upon the patient as well as in postoperative adjustment and modifications.
Thus, there exists a substantial need for an external fixation device, which when mounted upon a patient provides sufficient rigidity to completely immobilize the bone fracture, provides relatively unlimited pin placement, and permits ready access to the fracture sight for soft tissue treatment.